CN103215037A - Method for synthesizing upconversion fluorescence hollow nanosphere based on sodium polyacrylate microsphere template synthesis - Google Patents

Abstract

The invention belongs to the field of nanocomposite materials, and in particular relates to a preparation method for synthesizing up-conversion fluorescent hollow nanospheres with sodium polyacrylate microsphere templates. Using sodium polyacrylate microspheres as templates, multicolor up-conversion fluorescent digadolinium trioxide mesoporous hollow nanospheres were synthesized. First, sodium polyacrylate microspheres were prepared by adding sodium polyacrylate to water and isopropanol system. Then, using sodium polyacrylate microspheres as a template, through ion exchange between rare earth ions and sodium ions, rare earth ions replace sodium ions and coordinate with the carboxyl groups of sodium polyacrylate microspheres to form a polymeric precursor shell. Alcohol repeated cleaning several times. Afterwards, lanthanide-doped upconversion fluorescent hollow gadolinium trioxide spheres were obtained after calcination at 600 °C for 2 h. The method of the invention is simple and fast, has mild conditions and is environmentally friendly. Can be used for drug delivery, up-conversion fluorescence cell imaging and magnetic resonance imaging. They can also be used as catalysts, chemical reactors, bioimaging probes, and drug delivery systems.

Description

Method for Synthesizing Up-Conversion Fluorescent Hollow Nanospheres Using Sodium Polyacrylate Microsphere Template

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technical field

    The invention belongs to the field of nanocomposite materials, and in particular relates to a preparation method for synthesizing up-conversion fluorescent hollow nanospheres with sodium polyacrylate microsphere templates.

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Background technique

Up-conversion luminescence refers to the luminescence phenomenon in which rare earth ions absorb two or more low-energy photons and radiate one high-energy photon, usually referring to the conversion of near-infrared light to visible light. So far, up-conversion materials are mainly solid compounds doped with rare earth elements. Using the metastable energy level characteristics of rare earth elements, they can absorb multiple low-energy long-wave radiations, thereby turning infrared light invisible to the human eye into visible light. Compared with traditional fluorescent materials, such as organic fluorescent dye molecules and semiconductor quantum dots, it shows excellent characteristics, narrow-band emission with large stokes shift, long fluorescence lifetime, stable optical properties, low background fluorescence and stray scattered light, deep Excellent light penetration size, multi-color marking, etc. In recent years, up-conversion luminescence labeling uses near-infrared continuous laser as the excitation source, which has significant advantages such as deep light penetration depth, no biological background fluorescence interference, and no damage to biological tissues. It can be compared with ordinary confocal fluorescence imaging systems. Well combined, it can image biological samples labeled with multiple probes at the same time, and can display more details in complex biological samples. This imaging technology has broad application prospects in chemistry, material science and medical research. Among them, the upconversion fluorescent nanomaterials with mesoporous hollow structure have attracted much attention because of their high specific surface area, large capacity, stronger optical properties and wide application. Based on the above advantages, many research groups have devoted themselves to the synthesis of upconversion fluorescent hollow nanospheres.

At present, conventional synthesis methods include template method and ion exchange method. In the template method, surface-modified nanospheres are used as a template to grow an up-conversion fluorescent layer on the surface of the template, and then remove the template by etching or calcining to obtain a product. Yuliang Zhao et al. successfully prepared rare earth-doped gadolinium trioxide hollow nanospheres on a large scale by using hydrothermal carbon spheres as sacrificial templates by template method. Hongjie Zhang et al. used melamine-formaldehyde microspheres as templates, and then removed the templates by heat treatment, and successfully synthesized digadolinium trioxide microspheres with hollow structures (references: (a) G. Tian, Z. Gu, X. Liu , L. Zhou, W. Yin, L. Yan, S. Jin, W. Ren, G. Xing, S. Li and Y. Zhao, J. Phys. Chem. C, 2011, 115, 23790; (b) Z. R. Shen, J. G. Wang, P. C. Sun, D. T. Ding and T. H. Chen, Chem. Commun., 2009, 13, 1742; (c) J. U. Park, H. J. Lee, W. Cho, C. Jo and M. Oh, Adv. Mater ., 2011, 23, 3161.). The ion exchange method has also attracted the attention of many research groups. Jun Lin et al. introduced vanadium ions into the Gd(OH)CO ₃ :Ln ³⁺ precursor and obtained lanthanide-doped Hollow GdVO ₄ spheres (References: X. Kang, D. Yang, Y. Dai, M. Shang, Z. Cheng, X. Zhang, H. Lian, P. Ma and J. Lin, Nanoscale , 2013, 5, 253.). Fan Zhang et al obtained α-NaYF ₄ hollow spheres by ion exchange reaction between HF and Y ₂ O ₃ nanoparticles (References: F. Zhang, Y. Shi, X. Sun, D. Zhao and G. D. Stucky, Chem. Mater. , 2009, 21, 5237.).

However, these methods for preparing upconversion fluorescent hollow spheres have complicated synthesis steps, require high reaction temperature and long reaction time. The reagents required for the reaction are not mild enough and green, mostly volatile organic reagents and highly corrosive HF or NaOH solutions. Based on the above shortcomings of existing methods, it is urgent to develop a simple, green, economical and effective, large-scale , a general method with mild reaction conditions.

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Contents of the invention

The purpose of the present invention is to provide a general preparation method for synthesizing up-conversion fluorescent hollow nanospheres based on sodium polyacrylate microsphere template, the synthesis method is simple, the operation is convenient, and the obtained nanocapsules have many functions.

The invention uses sodium polyacrylate microspheres as templates to synthesize multicolor up-conversion fluorescent digadolinium trioxide mesoporous hollow nanospheres.

The scheme of the present invention is: firstly, sodium polyacrylate is added into the water and isopropanol system to prepare sodium polyacrylate microspheres. Then, using sodium polyacrylate microspheres as a template, through ion exchange between rare earth ions and sodium ions, rare earth ions replace sodium ions and coordinate with the carboxyl groups of sodium polyacrylate microspheres to form a polymeric precursor shell. Alcohol repeated cleaning several times. Afterwards, lanthanide-doped upconversion fluorescent hollow gadolinium trioxide spheres were obtained after calcination at 600 °C for 2 h.

The purpose of the present invention is achieved through the following scheme: a general preparation method for synthesizing up-conversion fluorescent mesoporous hollow nanospheres based on sodium polyacrylate microsphere templates, comprising the following steps:

1. The preparation method of sodium polyacrylate (PAAS) microspheres: Take 0.5-1 mL 0.2 g mL ^-1 PAAS aqueous solution, add 5-15 mL deionized water to it and stir evenly, then add 40- 200 mL of isopropanol (IPA), stirring continuously for 20-40 min, to obtain PAAS microsphere solution for later use;

2. Preparation method of lanthanide-doped polymeric precursor (PAA-Ln):

(1) Take 2-4 mL of the above-mentioned PAAS microsphere solution, add 0.1 M GdCl ₃ : YbCl ₃ : ErCl ₃ deionized water-IPA mixed solution and sonicate for 10-50 min. After the reaction is completed, wash with IPA for 5-7 For the second time, unreacted substances are completely removed, and finally the prepared PAA-Ln precursor is put into a 50 ° C oven for drying;

(2) In order to synthesize multicolor upconversion fluorescent mesoporous hollow nanospheres, different rare earth elements can be added to adjust the molar ratio of rare earth elements to prepare multicolor upconversion fluorescent mesoporous hollow nanospheres. Gd ³⁺ :Yb ³⁺ (Y ³⁺ )/Er ³⁺ (Tm ³⁺ , Ho ³⁺ ) in Gd ₂ O ₃ :Yb ³⁺ /Er ³⁺ , Gd ₂ O ₃ :Yb ³⁺ /Tm ^{3 +} , Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ , Gd ₂ O ₃ :Yb ³⁺ /Ho ³⁺ and Gd ₂ O ₃ :Y ³⁺ /Ho ³⁺ the molar ratios are: 80: 18:2, 79.8:20:0.2, 80:18:2, 79.6:20:0.4 and 79.6:20:0.4.

3. Preparation method for synthesizing multicolor upconversion fluorescent mesoporous hollow nanospheres based on sodium polyacrylate microsphere template: calcining the product of step 2 at 400-600 °C for 2~4 h to obtain sodium polyacrylate microsphere template synthesis upconversion Fluorescent mesoporous hollow nanospheres.

The multicolor up-conversion fluorescent hollow gadolinium trioxide spheres are prepared by the above method. Compared with traditional methods, the present invention has the following advantages:

1. The present invention proposes a method for synthesizing sodium polyacrylate microspheres in a water-isopropanol system for the first time. The method is simple and fast, with mild conditions and environmental protection.

2. The carboxyl functional groups on the surface of the sodium polyacrylate microspheres prepared by the present invention can coordinate with rare earth ions, so they can be used as functional templates in the synthesis of upconversion hollow nanospheres.

3. In the process of synthesizing multi-color up-conversion fluorescent mesoporous hollow nanospheres, the present invention avoids complicated treatment process and use of harmful reagents.

4. In the process of synthesizing up-conversion fluorescent mesoporous hollow nanospheres in the present invention, no template modification or special treatment is required, so the method is simple and convenient.

5. The multicolor up-conversion fluorescent hollow digadolinium trioxide spheres obtained in the present invention have better dispersion and larger hollow structure, so they can be used for drug delivery, up-conversion fluorescent cell imaging and magnetic resonance imaging.

6. The conditions of the present invention are simple, mild, natural and environmentally friendly, and can be extended to the synthesis of other hollow nanomaterials, which can be used as catalysts, chemical reactors, bioimaging probes and drug delivery systems.

The invention provides a preparation method of novel multicolor up-conversion fluorescent mesoporous hollow nanospheres, using sodium polyacrylate microspheres as a template, the method is environmentally friendly, the conditions are mild, easy to operate, the method is universal, and the obtained nanoparticles have good dispersibility and can be used in biological It has broad application prospects in many fields such as treatment and clinical medicine.

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Description of drawings

Accompanying drawing 1, is the transmission electron micrograph of the sodium polyacrylate microsphere that the present invention prepares;

Accompanying drawing 2, is the transmission electron microscope figure of the polymerization precursor doped with lanthanide element that the present invention prepares;

Accompanying drawing 3, is the transmission electron micrograph of the red upconversion fluorescent hollow Gd ₂ O ₃ :Yb ³⁺ /Er ³⁺ nanospheres prepared by the present invention;

Accompanying drawing 4, is the nitrogen adsorption diagram and the pore size distribution diagram of the red upconversion fluorescent hollow Gd ₂ O ₃ :Yb ³⁺ /Er ³⁺ nanospheres prepared by the present invention;

Accompanying drawing 5, is the up-conversion fluorescence spectrum diagram of the red up-conversion fluorescent hollow Gd ₂ O ₃ :Yb ³⁺ /Er ³⁺ nanospheres prepared by the present invention;

Accompanying drawing 6 is the transmission electron micrograph of the blue up-conversion fluorescent hollow Gd ₂ O ₃ :Yb ³⁺ /Tm ³⁺ nanospheres prepared by the present invention; accompanying drawing 7 is the green up-conversion fluorescent hollow prepared by the present invention TEM image of Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ nanospheres;

Accompanying drawing 8 is the transmission electron micrograph of the red up-conversion fluorescent hollow Gd ₂ O ₃ :Yb ³⁺ /Ho ³⁺ nanospheres prepared by the present invention;

Accompanying drawing 9 is the transmission electron microscope image of dark green color up-conversion fluorescent hollow Gd ₂ O ₃ :Y ³⁺ /Ho ³⁺ nanospheres prepared by the present invention.

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Detailed ways

Example 1:

Preparation of red upconversion fluorescent mesoporous Gd ₂ O ₃ :Yb ³⁺ /Er ³⁺ and Gd ₂ O ₃ :Yb ³⁺ /Ho ³⁺ hollow nanospheres based on polyacrylate sodium microsphere template:

(1) Synthesis of sodium polyacrylate (PAAS) microspheres: at room temperature, take 0.5 mL of 0.2 g mL ^-1 PAAS aqueous solution, add 10 mL of deionized water and stir well, then add 40 mL of Isopropanol (IPA), stirring continuously for 20 min, to obtain a well-dispersed PAAS microsphere solution for subsequent use (the volume ratio of water and isopropanol is 1:4);

(2) Take 4 mL of the above PAAS microsphere solution, add 320 μL of 0.1 M GdCl ₃ : YbCl ₃ : ErCl ₃ (Gd ³⁺ :Yb ³⁺ /Er ³⁺ =80:18:2) or GdCl ₃ : YbCl ₃ : HoCl ₃ (Gd ³⁺ :Yb ³⁺ /Ho ³⁺ =79.6:20:0.4) deionized water-IPA mixed solution was sonicated for 20 min. After the reaction was completed, it was washed 5 times with IPA and centrifuged to completely remove unreacted The substance, finally the precursor body prepared is put into 50 DEG C of baking ovens and dries;

(3) Calcining the white powder obtained in step (2) at 600 °C for 2 h (before 600 °C, heat up in an argon atmosphere at a rate of 2 °C min ^-1 , and the temperature reaches 600 °C Afterwards, calcined in the air atmosphere for 2 h), in the process of forming the shell of rare earth oxide, the template decomposition is simultaneously removed, after cooling down to room temperature naturally, the red up-conversion fluorescent mesoporous Gd ₂ O ₃ :Yb ³⁺ / Er ³⁺ and Gd ₂ O ₃ : Yb ³⁺ /Ho ³⁺ hollow nanospheres.

Example 2:

Synthesis of green upconversion fluorescent mesoporous Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ hollow nanospheres based on polyacrylate sodium microsphere template:

(1) with embodiment 1;

(2) Take 4 mL of the above PAAS microsphere solution, add 320 μL of 0.1 M GdCl ₃ : YCl ₃ : ErCl ₃ (Gd ³⁺ :Y ³⁺ /Er ³⁺ =80:18:2) deionized water- The IPA mixed solution was ultrasonicated for 20 min, and the others were the same as in Example 1;

(3) with embodiment 1.

Example 3:

Synthesis of blue upconversion fluorescent mesoporous Gd ₂ O ₃ :Yb ³⁺ /Tm ³⁺ hollow nanospheres based on polyacrylate sodium microsphere template:

(1) with embodiment 1;

(2) Take 4 mL of the above PAAS microsphere solution, add 320 μL of 0.1 M GdCl ₃ : YbCl ₃ : TmCl ₃ (Gd ³⁺ :Yb ³⁺ /Tm ³⁺ =79.8:20:0.2) deionized water- The IPA mixed solution was ultrasonicated for 20 min, and the others were the same as in Example 1;

(3) with embodiment 1.

Example 4:

Synthesis of dark green upconversion fluorescent mesoporous Gd ₂ O ₃ :Y ³⁺ /Ho ³⁺ hollow nanospheres based on polyacrylate sodium microsphere template:

(1) with embodiment 1;

(2) Take 4 mL of the above PAAS microsphere solution, add 320 μL of 0.1 M GdCl ₃ : YCl ₃ : HoCl ₃ (Gd ³⁺ :Y ³⁺ /Ho ³⁺ =79.6:20:0.4) deionized water- The IPA mixed solution was ultrasonicated for 20 min, and the others were the same as in Example 1;

(3) with embodiment 1.

Claims (1)

1. the method for the synthetic up-conversion fluorescence hollow nanospheres of sodium polyacrylate microsphere template is characterized in that comprising the steps:

One, the preparation method of sodium polyacrylate PAAS microballoon: get 0.5-1 mL 0.2 g mL ^-1The PAAS aqueous solution, 5-15 mL deionized water and stirring is even to wherein adding, and then to this mixed solution and dripping 40-200 mL Virahol IPA, continues to stir 20-40 min, and it is standby to obtain the PAAS microspheres solution;

Two, the preparation method of lanthanide-doped polymerization precursor PAA-Ln:

(1) gets above-mentioned PAAS microspheres solution 2-4 mL, add the GdCl of 0.1 M ₃: YbCl ₃: ErCl ₃The ultrasonic 10-50 min of deionized water-IPA mixing solutions, after reaction is finished, clean 5-7 time with IPA, remove unreacted matters fully, at last the PAA-Ln precursor for preparing is put into 50 ° of C oven for drying;

(2) be synthetic up-conversion fluorescence hollow nanospheres,, regulate the molar ratio of rare earth element, preparation polychrome up-conversion fluorescence hollow nanospheres, Gd by adding different rare earth elements ³⁺: Yb ³⁺(Y ³⁺): Er ³⁺(Tm ³⁺, Ho ³⁺) at Gd ₂O ₃: Yb ³⁺/ Er ³⁺, Gd ₂O ₃: Yb ³⁺/ Tm ³⁺, Gd ₂O ₃: Y ³⁺/ Er ³⁺, Gd ₂O ₃: Yb ³⁺/ Ho ³⁺And Gd ₂O ₃: Y ³⁺/ Ho ³⁺Molar ratio in the system is respectively: 80:18:2,79.8:20:0.2,80:18:2,79.6:20:0.4 and 79.6:20:0.4;

Three, the preparation method who synthesizes polychrome up-conversion fluorescence hollow nanospheres based on the sodium polyacrylate microsphere template: product 400-600 ° of C calcining 2 ~ 4 h with step 2 obtain the synthetic up-conversion fluorescence hollow nanospheres of sodium polyacrylate microsphere template.

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